1. Field of the Invention
The present invention relates to a ceramic device which is made of a sinter of calcium phosphate compound, having an excellent bio-compatibility to provide an environment for the promotion and formation of new bone mass (material).
2. Description of Related Art
Artificial elements have been implanted to recover the function of hard tissue or soft tissue of a living organism. Such implant materials that are known include metals, plastics, ceramics and composite ceramics. One of the most significant requirements for the implant material is to be bio-compatible with the receiver. From this view point, ceramic materials are considered ideal because ceramic is less harmful and more stable than other materials. Among the group of ceramic materials, it has been found that calcium phosphate compounds have a composition similar to the hard tissue of living organisms and accordingly, have been identified to be optimum implant materials. Indeed, calcium phosphate compounds have been used as artificial bones, and particularly, as a prosthesis for missing parts of bone.
In the case where a porous calcium phosphate compound is used to replace a missing segment of a bone, it is chosen due to its porous nature and that it bonds well with the natural bone. It has been observed that part of the natural bone grows into and is absorbed by the pores of the calcium phosphate compound, which becomes part of the new living bone structure. Consequently, porous calcium phosphate compound ceramics have been widely used as implant materials.
Nevertheless, there is no substantial analysis or study of a correlation between the form of the pores that constitute the porous material and the formation of the bone. Even for porous implant materials which are available in the market place, the above-mentioned correlation has not been taken into account when designing or administering these materials. For instance, if a pore which should be connected with an outer surface of the material is covered, no transport of body fluids within the implant material can be established and therefore, little new bone mass is formed within the pore. Consequently, the implant material remains inactive, leading to an inadequate bond being formed between the implant material and the surrounding living bone. In this case, the implant material is identified as foreign matter and is rejected by the living body. Furthermore, if there are a large number of pores through which living cells and body fluids can flow, then the formation of new bone mass within the pore requires much more time due to a free movement of the macro-phage, macro foreign cells within the implant material. Therefore, the implant material cannot satisfactorily achieve the proper function thereof due to lack of calcification. As can be seen from the foregoing, the pores are very important factors in determining the quality of the new bone structure. Nevertheless, conventional porous implanting materials have not been sufficiently studied from a scientific or functional view point.